Mobile base and X-ray machine mounted on such a mobile base

ABSTRACT

A mobile platform and a mobile base designed to support a device such as an X-ray machine is provided. The platform or base is configured to move using a motor-driven system associated with a navigation system. The navigation system enables the platform or base and any device supported by the platform or base (if any) to be moved automatically and with precision from one position to another within any defined space such as an examination, hybrid or operation room. An X-ray machine configured for mounting on the base is also provided. The X-ray machine is configured to move about the patient while at the same time keeping the region to be subjected to radiography within an X-ray beam.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.15/376,295, filed Dec. 12, 2016, which is a continuation of U.S.application Ser. No. 14/867,256, filed Sep. 28, 2015, now U.S. Pat. No.9,545,235, which is a continuation of U.S. application Ser. No.13/513,315, filed Jun. 1, 2012, now U.S. Pat. No. 9,173,628, which is afiling under 35 U.S.C. § 371(c) and claims priority to internationalpatent application number PCT/IB2010/003012, filed on Nov. 4, 2010,published on Jun. 9, 2011, as WO 2011/067648, which claims priority toFrench Patent Application Serial No. 0958556, filed Dec. 1, 2009, nowFrench Patent No. 2953119, all of which are incorporated herein byreference in their respective entireties.

BACKGROUND

X-ray diagnostic machines are X-ray image acquisition machines. Thesemachines are used to obtain images or even sequences of images of anorgan situated inside a living being, especially a human being.

X-ray machines have moving parts that enable them to rotate about thepatient in different directions. These moving parts are capable ofmoving in all three dimensions of a space. These moving parts generallyconsist of an arm having an X-ray tube at one of its ends and a detectorat the other one of its ends. This tube sends out an X-ray beam along adirection of emission.

These X-ray machines are used for angiography examinations fordiagnostic or interventional purposes.

During these examinations, it is necessary to take X-ray exposures ofthe region undergoing diagnosis or intervention. To this end, thepatient is positioned between the X-ray tube and the detector and morespecifically he or she is placed so that the region to be X-rayed is ina facing position.

There presently exists several types of X-ray machines used to carry outthe radiography exposures, for example X-ray machines fixed to theground in an examination room. These X-ray machines have several degreesof freedom by which the X-ray beam can be positioned before the regionof interest. However, this type of X-ray machine is not suited to anoperating ward. Indeed, for certain examinations, X-rays are needed onlyat the beginning and at the end of the operation. In between these twopoints, the emphasis is on access to the patient. Since theseangiography machines are fixed to the ground, they cannot be moved awayfrom the patient support table or bed at a time when the presence of theradiography system is not necessary. Furthermore, the stages of placingand moving the patient on the table become more difficult because thisbulky system cannot be moved away.

There also exist X-ray machines called “mobile surgical units” that canbe moved manually. These machines generally have a large trolleysupporting a large number of batteries used to power the X-ray tube.However, this type of X-ray machine has drawbacks. Indeed, thesemachines are not suited to angiography procedures. For the necessarypower delivered by the X-ray tube is not sufficient to perform theangiography procedures which require excellent image quality.

Furthermore, these mobile X-ray machines do not provide for complexangular movements because the diameter of the arm that supports the tubeand the detector is not big enough. Similarly, these mobile X-raymachines do not reach sufficient rotation speeds to enable high quality3D image reconstruction like those needed in a present-day angiographymachine. These mobile X-ray machines are also not suited to angiographyprocedures requiring certain automated motions needed for certainapplications, especially 3D reconstruction.

Furthermore, even if the weight of such a machine is half that of anX-ray machine intended for angiography, it is still very difficult tomove because of its large size and its weight (about 300 kg).

There are also X-ray machines for angiography that are suspended fromthe ceiling and can be moved on rails all along the ceiling, through amobile trolley and by means of an electrical motor. However, this typeof X-ray machine has drawbacks. Indeed, an operation room generally hasa patient's support table, lighting means, systems to distribute medicalfluids, supports for anesthetic equipment, supports for electricalscalpels and supports for perfusion pumps. Most of these systems arefixed to the ceiling around the patient's table depending on theconstraints of an operations room, thus cluttering the space around thepatient's table. Consequently, owing to the space requirement of therails fixed to the ceiling and the volume of the X-ray machine, theirinstallation in a surgical ward as an angiography machine is quiteimpossible.

Furthermore, the fact of mounting an X-ray machine on the ceilingconsiderably increases the risk of opportunistic infection in thepatient. Indeed, these X-ray machines suspended on the ceiling aredesigned to be positioned above the patient or in his immediate vicinityand therefore in the immediate vicinity of the operating site thusincreasing the risk of particles falling from the machine.

Furthermore, this fact of suspending the X-ray machine or machine givesrise to difficulties in cleaning and maintaining this machine properly.Thus, it becomes impossible to mount this type of X-ray machine adaptedto environments of varying sterility. Indeed, operating rooms areconstantly sterilized and the fact of having rails on which the X-raymachine slides above the patient increases the risks of nosocomialillness or septicemia owing to the difficulty of cleaning theseapparatuses

Furthermore, in certain surgical wards, a sterile laminar flow is set upabove the patient. In this case, the rails enable the machine to be madeto slide on the ceiling with the laminar flow, and this has the effectof blowing particles present on the into the sterile zone.

There also exist X-ray machines for angiography based on the technologyof industrial robots generally found in automobile plants. However,X-ray machines of this type have drawbacks. Indeed, the arms fitted tothese robots generally have a relatively substantial space requirementfor the space available in a surgical ward. Consequently, the movementof these arms creates risks of safety for people working in a surgicalward. Consequently, the installation of these robots as angiographymachines in a surgical ward is quite impossible.

The need has become felt for some time now for an X-ray machine suitedto what are called hybrid rooms, making it possible: firstly to meet theneeds of angiography, especially by a system equipped with an X-ray tubehaving sufficient power to enable high image quality and 3Dreconstruction, and secondly to meet the needs of operating roomsespecially through a system that is capable of moving the X-ray machine

SUMMARY

Embodiments of the subject matter disclosed herein generally relate to amobile base designed to receive an X-ray machine, and also to an X-raymachine that can be mounted on said mobile base. Embodiments of thedisclosure find application in medical imaging, and more particularly inthe field of medical diagnostic apparatuses.

The X-ray machine described herein is designed especially for a hospitalward, such as a surgical ward, an anesthetic room, a diagnostic unit, anintensive care unit or a ward known as a hybrid ward used to meet therequirements of both angiography rooms and operation rooms.

According to a non-limiting embodiment of the present disclosure, amobile base on which is mounted an X-ray machine comprising an X-raytube configured to emit an X-ray beam along a direction of emission, andan X-ray detector aligned in the direction of emission of the X-ray beamand positioned to face the X-ray tube, is provided. The mobile basecomprises: at least two motorized drive wheels spaced away from eachother, each motorized drive wheel configured to rotate independently ofthe other wheel; a positioning system configured to provide the data onposition of the X-ray machine; a processing unit coupled to the at leasttwo motorized drive wheels and the positioning system, wherein theprocessing unit is configured to receive an instruction value ondestination and trajectory, receive data on position of the X-raymachine, and to generate as an output a command, such as rotationaldirection and/or speed command, for each drive wheel.

According to another non-limiting embodiment of the present disclosure,an X-ray machine is provided. The X-ray machine comprises: an X-ray tubeconfigured to emit an X-ray beam along a direction of emission; an X-raydetector aligned in the direction of emission of the X-ray beam andpositioned to face the X-ray tube, wherein the X-ray machine is mountedon a mobile base comprising: at least two motorized drive wheels spacedaway from each other, each drive wheel configured to rotateindependently of the other wheel; a positioning system configured toprovide the data on position of the X-ray machine; a processing unitcoupled to the at least two motorized drive wheels and the positioningsystem, wherein the processing unit is configured to receive aninstruction value on destination and trajectory, receive data onposition of the X-ray machine, and to generate as an output a command,such as rotational direction and/or speed command, for each drive wheel.

According to another non-limiting embodiment of the present disclosure,a mobile base to support a medical imaging machine is provided. Saidbase comprises: at least two motorized drive wheels spaced away fromeach other, each of the at least two motorized drive wheels configuredto rotate independently of one another in either rotational directionrelative to a respective axis of rotation; a positioning systemcomprising a gyrolaser, a reading system and a memory, the positioningsystem configured to compute position data corresponding to a positionof the medical imaging machine in a predefined fixed referential systemon the basis of reflections from reflectors positioned about a definedspace, the positions of the reflectors stored in the memory; and aprocessing unit in communication with the at least two motorized drivewheels and the positioning system, and configured to receive theposition data and to generate as an output a respective command for eachof the at least two wheel motorized drive wheels to move and orient themobile base to one or more desired positions in the defined space.

According to another non-limiting embodiment of the present disclosure,an X-ray machine is provided. The X-ray machine comprises: an X-ray tubeconfigured to emit an X-ray beam along a direction of emission; and anX-ray detector aligned in the direction of emission of the X-ray beamand positioned to face the X-ray tube, wherein the X-ray machine ismounted on a mobile base comprising: at least two motorized drive wheelsspaced away from each other, each of the at least two motorized drivewheels configured to rotate independently of one another in eitherrotational direction relative to a respective axis of rotation; apositioning system comprising a gyrolaser, a reading system and amemory, the positioning system configured to compute position datacorresponding to a position of the medical imaging machine in apredefined fixed referential system on the basis of reflections fromreflectors positioned about a defined space, the positions of thereflectors stored in the memory; and a processing unit in communicationwith the at least two motorized drive wheels and the positioning system,and configured to receive the position data and to generate as an outputa respective command for each of the at least two wheel motorized drivewheels to move and orient the mobile base to one or more desiredpositions in the defined space.

According to another non-limiting embodiment of the present disclosure,a mobile platform is provided. The mobile platform comprises at leasttwo motorized drive wheels spaced away from each other, each of the atleast two motorized drive wheels configured to rotate independently ofone another in either rotational direction relative to a respective axisof rotation; a positioning system comprising a gyrolaser, a readingsystem and a memory, the positioning system configured to computeposition data corresponding to a position of the mobile platform in apredefined fixed referential system on the basis of reflections fromreflectors positioned about a defined space, the positions of thereflectors stored in the memory; and a processing unit in communicationwith the at least two motorized drive wheels and the positioning system,and configured to receive the position data and to generate as an outputa respective command for each of the at least two wheel motorized drivewheels to move and orient the mobile platform to one or more desiredpositions in the defined space.

In any of the embodiments described herein (infra or supra), the atleast two drive wheels are configured to rotate at the same speed or atvariable speeds relative to one another.

In any of the embodiments described herein (infra or supra), the mobilebase or platform may further comprise a traction encoder mounted on theat least two motorized drive wheels and a direction encoder, wherein thetraction encoder and the direction encoder are configured to providedata relative to a position of the X-ray machine.

In any of the embodiments described herein (infra or supra), the mobilebase or platform may further comprise a braking apparatus configured tostop the mobile base or platform when moving and/or prevent the basefrom moving from a parked position.

In any of the embodiments described herein (infra or supra the mobilebase or platform may further comprises a user interface in communicationwith the processing unit for entering at least one of instructed valuescorresponding to at least one of destination, trajectory, speed,position and orientation of the mobile base.

And in any of the embodiments described herein (infra or supra), thepositioning system can be any form of positing or navigation systemknown to those skilled in the art such as, for example, an opticalpositioning system, global positioning system (GPS), a local positioningsystem (LPS), a real time locating system, an electromagneticpositioning system, a radar positioning system, and a sonar positingsystem.

BRIEF DESCRIPTION OF THE DRAWINGS

The non-limiting embodiments described herein will be understood moreclearly from the following description and accompanying figures.

FIGS. 1 and 2 are a schematic representation of a vascular type X-raymachine mounted on a mobile base, according to a non-limiting embodimentof the present disclosure.

FIG. 3 is a schematic view of a support structure of a mobile base onwhich the X-ray machine is mounted, according to a non-limitingembodiment of the present disclosure.

FIG. 4 is a schematic illustration of modules for implementing theoperation of the X-ray machine controlled by a processing unit,according to a non-limiting embodiment of the present disclosure.

FIG. 5 is a schematic and detailed view of the processing unit of FIG.4, according to a non-limiting embodiment of the present disclosure.

FIG. 6 is a schematic view of a man-machine interface of the X-raymachine used to enter instructed values of destination for saidapparatus, according to a non-limiting embodiment of the presentdisclosure.

FIG. 7 is a schematic view of the X-ray machine moved by means of themobile base in a room along a predefined path, according to anon-limiting embodiment of the present disclosure.

FIG. 8 is a graphic representation of an absolute position of the mobilebase in a fixed Cartesian reference system, according to a non-limitingembodiment of the present disclosure.

FIG. 9 is a perspective view of the freewheel system, according to anon-limiting embodiment of the present disclosure.

FIG. 10 is a schematic view of two-motorized drive wheels spaced awayfrom each other, according to a non-limiting embodiment of the presentdisclosure.

FIG. 11 is a table showing different possible drive wheel rotationcombinations, according to a non-limiting embodiment of the presentdisclosure.

FIG. 12 is a graphic representation of a positioning system, accordingto a non-limiting embodiment of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 shows a vascular type X-ray machine 10 in an examination room orsurgical ward or hybrid room represented in the form of a framereferenced 9. The X-ray machine 10 has moving parts that can rotate indifferent directions around a patient. These moving parts are capable ofmoving in all three dimensions of a space. These moving parts are formedin general by an arm 13 comprising an X-ray tube 11, which is the X-raysource, at one of its ends and a detector 12 at another of its ends.This tube 11 is used to send an X-ray beam along a direction ofemission. In general, the arm 13 is C-shaped.

The detector 12 is hooked to the arm 13 opposite the tube 11 and in thedirection of emission. The X-ray tube 11 and the image detector 12 aremounted at the opposite ends of the arm 13 so that the X-rays emitted bythe tube 11 are incidental to and detected by the image detector 12. Thedetector 12 is connected to a lift 19 used to raise and lower saiddetector in the direction of emission.

The room 9 also has an examination table 14, or a bed, on which apatient reclines. The examination table 14 can be mounted on a frame 15fixed to the ground. The examination table 15 can also be an operationtable with a moveable frame.

During a radiography examination, the X-ray machine 10 is shifted inposition in working mode so that the organ to be examined is positionedin the X-ray beam.

The arm 13 is mounted on a mobile base or platform 16 through a supportelement 17. Although the mobile base described herein is described inconjunction with medical imaging equipment (e.g. an X-ray machine), itshould be noted that the mobile base or platform 16 is configured tomove any type of device or object disposed thereon; that is, the deviceor object on the base or platform should not be construed in a limitingsense. The support element 17 is mounted fixedly on the mobile base 16.The arm 13 is connected to the support element 17 by means of a rotatingarm 18. The arm 13 is mounted so as to be sliding relative to therotating arm 18. The rotating arm 18 rotates about an axis passingthrough the X-ray beam. This rotating assembly of the arm 18 on theelement 17 enables the X-ray tube 11 and the image detector 12 to beshifted rotationally around the arc of the rotating arm 18. The supportelement 17, the rotating arm 18 and the arm 13 are thus all three hingedrelative to one another. This hinging enables the X-ray machine 10 tomove in three dimensions. This movement in three dimensions of themoving parts of the X-ray machine 10 is used to achieve images of theorgan to be examined at different values of incidence.

By combining the rotational motions of the moving parts of the X-raymachine 10, the X-ray beam can describe all the directions of emissionof the X-rays included within a sphere whose center correspondsapproximately to an isocenter 69 of the X-ray machine 10 with a diametersubstantially equal to the distance between the tube 11 and the detector12. The isocenter 69 is situated in a space included between the X-rayemission tube 11 and the X-ray reception detector 12. The isocenter 69corresponds to the center of the arc of a circle made by the arm 13. Themobile base 16 is designed to move the X-ray machine 10 on the ground.The mobile base 16 is controlled automatically by a processing unit 50.This processing unit 50 can be embedded in the mobile base or kept at adistance in a control room which can be situated outside the examinationroom 9. In the latter case, the mobile base 16 can be controlled througha radiofrequency or wire type connection using any type ofcommunications protocol.

FIG. 2 provides a detailed view of the characteristics of the mobilebase 16. As illustrated in FIG. 3, the mobile base 16 has a supportstructure 39. This structure may comprise several parts joined byscrewing or by soldering. This structure 39 may also be a cast element.This support structure 39 has a set of structural parts whose joiningand geometrical configuration are designed so that: a suitable supporton the ground is provided for the mobile base 16 by a deformation of theset of structural parts forming the support structure 39, and the mobilebase 16 is given the rigidity that is necessary and sufficient toeliminate the problem of hyperstatism which may be caused by the fourwheels of the mobile base 16 laid on the ground. The structural support30 ensures that all four wheels of the mobile base 16 will bepermanently in contact with the ground, supporting the apparatuses ofthe mobile base 16 which may be especially motors, wheels, a man-machineinterface etc. The layout of these apparatuses in the support structure39 is also designed so that the weight of the support structure 39 andof the apparatuses balances the weight of the X-ray machine 10.

The purpose of this balancing is to ensure the stability of the X-raymachine X-rays, even during a shift of the moving parts of said machine.The mobile base 16 thus has the role of a counterweight which means thatit can maintain the static and dynamic stability of the X-ray machine10, the apparatuses and the support structure 39. In one example, theweight of the base mobile may be in the range of 500 kg relative to theweight of the X-ray machine 10 which may be in the range of 300 kg.

The support structure 39 has a supporting arm 20 extending along thelongitudinal direction Yo of a Cartesian reference system Ro. Thesupporting arm 20 has, for example, a substantially tubular shape. Inone embodiment, the supporting arm 20 is one meter high and has arectangular section of 30 cm by 20 cm.

At one upper end 21, the supporting arm 20 has joining means 22,geometrically and structurally designed so as to receive the supportelement 17. In the example illustrated by the figures, the joining means22 and the support element 17 are circular. The joining means 22 may befixed to the support element 17, for example by a screw/nut system or bysoldering.

In a preferred embodiment, the mobile base 16 has a receiving means on aface 23 opposite the joining means 22. On these receiving means, it ispossible to mount a man/machine interface 24. FIG. 6 shows an example ofa man/machine interface 24.

The support structure 39 has a set 26 of rigid metal structures restingon the ground by means of wheels 36, 37 and 38. This set 26 is joinedwith the supporting arm 20. A front part of the set 26 is substantiallyY-shaped in the horizontal position. The set 26 has a baseplate 27situated on a rear part of the Y-shape fixedly joined to a crossbar 40.This baseplate 27 is the structural part connecting the set 26 to thesupporting arm 20.

The bar 40 is fixedly joined to an element formed by two arms 28 and 29having a corner. The fixed joining can be obtained by soldering or anyother type of fastening system. For reasons of resistance to stresses,it is generally necessary to line the edges of the arms 28 and 29 andthe edges of the crossbar 40 with a vertical reinforcement part 41 whichis a rigid lateral metal strip.

The baseplate 27 has a vertical frame 30 supporting a horizontal plate31 equipped with two turret features 52 shown in FIG. 4. A lower end 25of the supporting arm 20 is fixed to the frame 30. This fastening can beobtained by soldering or any other type of fastening system.

The choice of the materials, the dimensions, the shape and thethicknesses of the parts of the unit 26, the vertical reinforcementpieces 41 as well as the layout of these parts and reinforcement pieceswithin the internal structure provides mechanical characteristics ofrigidity to the unit 26 relative to the supporting arm 20. Thesemechanical characteristics of rigidity are designed to compensate forchanges in shape due to the weight of the machine 10 supported by themobile base 16 and to absorb vibrations and secondarily the noise of theX-ray machine 10. These mechanical characteristics enable the formationof points of stabilization of the X-ray machine 10 at the ends of thearms 28 and 29 and the baseplate 27.

In one example, the angle formed by the two arms 28 and 29 may be of theorder of 90 degrees and the height of the vertical reinforcement parts41 may be of the order of 20 centimeters.

In one embodiment, the flexible and noise-free material may furthermorebe inserted at the point where the crossbar 40 is fixedly joined to theframe 30 of the baseplate 27. This addition of flexible material isdesigned to reinforce the deformation of the support structure 39providing for a balanced support to the four wheels on the ground. Thisaddition of flexible material also improves the mechanicalcharacteristics of rigidity of the set 26 relative to the supporting arm20. In one embodiment, the flexible material is rubber. In oneembodiment, the supporting arm 20 and the Y-shaped unit 26 are made ofsteel.

Each of the two turret features 52 rotates about a vertical axis V. Eachturret is equipped respectively with a traction motor 34 and 35 and adirection motor 42 and 43. A wheel 36 is driven by the two motors,namely the traction motor 34 and the direction motor 42. A wheel 37 isdriven by the two motors, namely the traction motor 35 and the directionmotor 43. The direction motors 42 and 43 respectively provide forrotation of the wheel 36 and 37 on the vertical axis.

The mobile base 16 supports the two driving motor turret features 52.The two turret features 52 are fixed to the horizontal plate 31. To thisend, the horizontal plate 31 has two holes 32 and 33 configured so as torespectively receive one of the two turret features 52. Each of the twoturret features 52 can be controlled independently of the other.

The wheel 36 rotates at the speed A and is oriented at an angle α and awheel 37 rotates at the speed B and is oriented at an angle β. Thespeeds A and B are often different and the angles α and β are oftendifferent. These different speeds and angles of the two drive wheels 36and 37 enable the X-ray machine 10 to be moved in an examination room 9,in minimizing the volume traversed by said apparatus to the maximumextent. Indeed, the rotational center of the machine 10 can be placedanywhere by means of the different speeds and angles of the two wheels36 and 37. This independence also enables the machine 10 to moveparallel to the set 26. In general, the different speeds and angles ofthe two wheels 36 and 37 provide for all possible movements in anexamination room 9.

In another embodiment, shown in FIG. 10, the mobile base 16 has at leasttwo motorized drive wheels 36, 37 spaced away from each other, whereeach motorized drive wheel 36, 37 is configured to rotate independentlyof the other motorized drive wheel 36, 37. Each drive wheel 36, 37 iscoupled to one motor 100 rather than two motors, i.e., a traction motor34, 35 and a direction motor 42, 43. Relative to other embodiments, thedrive wheels 36, 37 in the present embodiment could be made lighterweight, however, this is not a requirement. The lighter drive wheels 36,37 eliminate wear and tear on the ground as the mobile base 16 movesthroughout the room 9.

While FIG. 10 shows a motor 100 with one drive wheel 36, 37, the motor100 can be associated with any number of drive wheels 36, 37. In anotherembodiment, the drive wheels 36, 37 can be spaced about in more than twolocations on the mobile base 16, with multiple motors 100 drivingmultiple drive wheels 36, 37.

In addition to what has been discussed above, it is possible for thedrive wheels 36, 37 to rotate in additional combinations. For example,as shown in FIG. 11, the at least two motorized drive wheels 36, 37 canrotate in the same direction around a horizontal axis; in an oppositedirection, relative to one another to change direction of the mobilebase 16; and with one wheel 36, 37 in reverse, or both wheels 36, 37rotating in reverse. Furthermore, the wheels 36, 37 can rotate atvarying speeds in the same or opposite direction to change direction ofthe mobile base 16. The table in FIG. 11 lists some possiblecombinations of wheel direction and speed, however, the list is notexhaustive.

The mobile base 16 furthermore has a freewheel system. This system hastwo free wheels 38 respectively mounted on a face before the ground ofone end of each arm 28 and 29 of the counterweight system 26. These twofreewheels 38 mounted rotationally are capable of undergoing rotationalmovements induced by the drive wheels 36 and 37.

The mobile base 16 thus has four multidirectional wheels so as to beable to move the machine 10 in every direction. These wheels are placed,symmetrically in sets of two, with the freewheel system whichconstitutes the front train and the driving and directional wheels 36and 37 which constitute the rear train. In one alternative embodiment,the wheels may be placed asymmetrically.

FIG. 9 shows a large-scale view in perspective of an example of afreewheel 38 mounted on the arm 28. It is known that this assembly isidentical for the arm 29.

A cover 44 is designed to receive a rotation pin 47 of the wheel 38. Anupper part 46 of the cover 44 is mounted, beneath the arm 28, so as topivot about a vertical rotation axis 48. This pivoting assembly can beobtained by means of a screw/nut fastening system providing for onedegree of freedom in rotation. A spacer 45 may go through a space madein the arm 28 to block the nut while at the same time enabling therotation of the rotational axis 48.

The vertical rotation axis 48 of the freewheel 38 is fixed so as to havean axis that is offset relative to the supporting base of the freewheel38 on the ground. When the mobile base 16 is shifted in a determineddirection, each free wheel gets oriented by rotation about the verticalrotation axis 48 so as to prevent the freewheel 38 from getting jammed.

The freewheel system may furthermore include a braking device designedto block the rotation of the freewheels 38 firstly about the verticalrotation axis 48 and secondly about the rotation shaft 47. In theexample of FIG. 9, the cover 44 has a braking device 49 comprising ablocking unit which is herein fixed to the peak of its lower part. Thisbraking device 49 can be controlled manually or remotely for example bymeans of the control unit 50. The braking device 49 is configured sothat its actuation causes the rotation of the wheels 38 to stop andimmobilizes it by blocking the rotation of the axis 48 and the shaft 47.

Thus, when the machine 10 is in the working position and at a stop, thefact that the freewheels 38 are immobilized prevents them from movingduring the phases of acceleration and deceleration of the moving partsof the machine 10.

The braking device 49 can be mounted in the rotation shaft 47 of thewheel 38 or at the spacer 45 and in the rotation axis 48. It can be madeby any type of existing braking device whose function is to stop thewheel 38 and to keep it stopped.

With the embodiments described herein, it is thus possible to easilychange the region of interest to be examined by: shifting the mobilebase 16 from one working position to another by means of the driving andsteerable wheels 36 and 37, and moving the moving parts to another givenorientation while at the same time keeping the organ to be examinedunder the X-ray beam.

It must be noted that the element with the arms 28 and 29 is positionedat a sufficient distance from the X-ray tube so that its front end,supporting the freewheels 38, do not come into collision with the hoodof the tube 11 in any of the positions that it may take. Thisconfiguration makes it possible to increase the distance between thetube 11 and the isocenter 69 of the X-ray machine 10. Through theshifting of the arm 13 along the arc, the tube 11 and the detector 12can rotate about the isocenter 69 while at the same time keeping theirface-to-face relationship. The tube 11 and the detector 12 arepositioned on either side of the patient, generally one of theseelements being on top of the patient and the other beneath the table 14which is transparent to X-rays. An increase in the distance between thetube 11 and the isocenter 69 releases the space situated beneath thetable 14 relative to the isocenter in order to enable not only theplacing of one of these elements but also its movement according todifferent, at times complex, angulations.

This increase in distance between the tube 11 and the isocenter 69 makesit possible to obtain an X-ray machine 10 capable of carrying outcomplex angulations and 3D reconstructions of organs situated at theperiphery of the body, for example the patient's liver. According tothis embodiment of the present disclosure, the distance between the tube11 and the isocenter 69 may be increased by about 10% as compared withan existing X-ray machine that is fixed to the ground and has the samemechanical geometry.

FIG. 4 is a block diagram of the working of the mobile base 16controlled by the processing unit 50. In the example of FIG. 4, only oneof the turret features 52 is represented, it being understood that thesecond turret feature which is not represented works identically. Inthis example, the turret feature 52 that is shown comprises the tractionmotor 34 and the direction motor 32 which are designed to drive thewheel 36.

The processing unit 50 is represented in detail in FIG. 5. Theprocessing unit 50 is connected to the DC or rectified power source 51.This source 51 may also be a rechargeable battery.

The processing unit 50 communicates especially with the interface 24and/or supervision computer which sends it especially the instructedvalues on destination.

In one embodiment, the processing unit 50 and the interface 24 areconnected through a communications bus 88.

In one alternative embodiment, the interface 24 may be set away from themobile base 16. In this case, it may be placed on the examination table14. The communications between the processing unit and the interface 24set at a distance may be obtained by means of a wireless link. Thewireless link may be of any type without departing from the framework ofthe embodiments described herein. For example it may be an infrared,ultrasonic, or radiofrequency link, based for example on an industrialstandard such as the ZigBee standard or a proprietary standard or againit may be obtained in a frequency band associated with a given protocolsuch as Wi-Fi, Bluetooth etc. To this end, the processing unit 50 has anantenna 52 which enables it to obtain a radio electrical link with theinterface 24 set at a distance.

Communications between the interface 24 set at a distance and theprocessing unit 50 can also be obtained through a wire link.

A representation of the man-machine interface 24 is illustrated in FIG.6. FIG. 6 shows a top view of the mobile base 16. The man-machineinterface 24 herein is a touchscreen 53. In on variant, this interface24 may be a screen associated with a keyboard. In another variant, theman-machine interface 24 comprises at least one of a touchscreen 53, ajoystick, and a remote control unit. The interface 24 may be powered bythe source 51. In one variant, it may be powered by a distinct energysource.

This touchscreen 53 has interface controls 54 displayed on the screen.These interface controls 54 correspond to predefined working and parkingpositions of the X-ray machine 10 in the room 9. The controls 54 may bedisplayed on the screen 53 by letters, figures or by a graphicrepresentation. This interface 24 is aimed at making it easy for anoperator to enter an instructed value of destination by pressing one ofthe interface controls 54 displayed on the screen 53. This interface 54is complemented by a set of control buttons such as emergency stopbuttons 55 or buttons for starting the mobile base 16.

The processing unit 50 is coupled to a position sensor 56. As oneskilled in the art will appreciate, the position sensor 56 could be anytype of known sensor that is capable of or configured to detect ormeasure position such as, for example, an optical position sensor. Theposition sensor 56 is mounted on an upper end of a connection pole 57. Alower end of the connection pole 57 is fixed to the supporting arm 20 ofthe mobile base 16. In one variant, the connection pole 57 may be fixedto the horizontal plate 31 in the vicinity of the supporting arm 20.This type of mounting of the pole 57 removes the need to transmit thevibrations of the supporting arm 20 to the sensor 56.

The position sensor 56 is used to measure an angle or an angular speedabout at least one axis. It can also be used for the precisionmeasurement of the position of the X-ray machine 10 relative to apredefined fixed reference system Ro (Xo, Yo).

In at least one non-limiting embodiment, the position sensor 56 shown inFIG. 2 can be a gyrolaser, which generally has inter alia a laseremitter device and a system for the rotation of the emitter device. Theemitter device emits a pulsed incident laser beam 68.

As can be seen in FIG. 7, the room 9 is preliminarily provided withlaser beam reflectors 58 placed at predetermined positions. Thesereflectors 58 may be catadioptric reflectors. The reflectors 58 areplaced on the demarcating walls of the room 9 at a height such that theycan detect the incident laser beam 68.

The positioning distance between two successive reflectors 58 isdetermined so as to increase the precision of the gyrolaser 56. In oneexample, the reflectors 58 may be at a height of about 2.5 m from theground and the minimum distance between two reflectors may be in therange of 2 m. In a room 9 having surface area of about 60 m², the numberof reflectors 58 may be of the order of 10.

When the incident laser beam 68 encounters a reflector 58, thisreflector 58 reflects towards the gyrolaser 56 which has a system forreading reflected laser beams.

The reading system 59 has means to measure the time taken by theincident beam to return to the gyrolaser 56. These measuring means arecapable of determining a distance with precision on the basis of thetime measured. The measuring means associate the determined distancewith an angular position by means of an encoder which is precise to atenth of a degree. To this end, a card comprising positions (coordinatesin the fixed reference system) of the set of reflectors 58 is recordedbeforehand in a data memory (not shown) of the reading system 59.Depending on the position of the reflectors 58 that have emitted thereflections received and on the angular speed, the reading system 59computes the angle Ω of orientation of the machine 10.

The reading system 59 also has computation means capable of determiningan absolute position of the gyrolaser 56 corresponding to that of theX-ray machine 10 as a function of the reflections received in one turnof the emission device and of the chart of positions of the reflectors58 recorded in the data memory.

The reading system 59 may be a computer. The actions performed by thisreading system 59 are arranged in order by a microprocessor (not shown).The microprocessor, in response to the instruction codes recorded in amemory, produces the angle α and the coordinates of the X-ray machine inthe fixed referential system.

FIG. 8 is a graphic representation of the X-ray machine 10 in aCartesian reference system. The orientation of the machine 10 isidentified by the angle Ω which corresponds to the orientation of alocal reference system R (x, y) in the fixed reference system Ro (Xo,Yo). The fixed reference system Ro corresponds to an initial referencein an idle phase of the machine 10 in the local reference system. Theangle Ω and the coordinates of the machine 10 in the local referencesystem R(x,y) are given by the gyrolaser 56.

The fixed reference system Ro is characterized by a set of unit vectors(i, j), respectively representing the direction of the axes OXo, OYo. Inone embodiment, the fixed reference system Ro is a Cartesian referencesystem joined to the examination table 14, when this table is fixed tothe ground through the frame 15. In this case, the x-axis OXo of thefixed reference system corresponds to the horizontal plane of theexamination table 14. In one variant, the fixed reference system Ro maybe any unspecified, predefined Cartesian reference system in the room 9.

The reading system 59 is coupled to the processing unit 50 by thecommunications bus 88 and transmits information elements to it on theangle Ω and on the coordinates of the machine 10 relative to the localreference system. These information elements constitute the absoluteposition of the machine 10.

The processing unit 50 drives the traction motor 34 and the directionmotor 42, proper to the wheels 36, in managing the supply of energy as afunction of the absolute position of the machine 10 and the path 67 tobe followed.

In another embodiment, the processing unit 50 is in communication withthe at least two motorized drive wheels 36, 37 and the positioningsystem 105. The processing unit 50 receives the position data from thepositioning system 105 and generates as an output a respective directionand speed to drive the at least two motorized drive wheels 36, 37.

Since, during one full rotation of the gyrolaser 56, the mobile base 16will have moved, the measurement of absolute position should besupplemented by other measurements to improve its position.

To obtain these supplementary measurements, an angular position sensor60 is planned on the direction motor 42. This angular sensor 60 is usedto find out the orientation of the driving and directional wheel 36 ateach instant. The angular position sensor 60 can be of many types, forexample an optical sensor, a resolver type or synchro type rotarytransformer sensor etc.

Furthermore, the traction motor 34 is also provided with a wheel speedsensor 61. The information coming from the signals of the set of sensors60 and 61 constitute the relative position of the machine 10. Thisrelative position of the machine 10 enables the processing unit 50 toupdate the absolute position should there be a decline in the precisionof the laser measurement.

At each point in time, the processing unit 50 makes a relatively preciseestimation of the speed of each wheel relative to the ground, bycombining data on the relative position of the machine 10 with data onabsolute position.

The traction motor 34 is controlled by a traction variator 62. Thedirection motor 42 is controlled by a direction variator 63. Thistraction variator 62 and direction variator 63 are connected to theprocessing unit 50 through the communications bus 88. The variators 62and 63 respectively receive instructed values of speed and directionfrom the processing unit 50 which they convert into current and intovoltage for each motor.

The traction variator 63 and the direction variator 63 are used togenerate an electrical differential as a function of the instructionssent out by the processing unit.

These differentials are designed to share the propulsion force and therotational angles between the two wheels 36 and 37 so that they cantravel along the programmed path 67. The processing unit 50, using thevariators, dictates the currents in the traction and direction motors asa function of information representing especially the speed and angulardirection of the driving wheels 36 and 37 as measured, and instructedvalues on the positioning of the operator, the absolute position of theX-ray machine 10 and the path 67 to be followed.

The machine 10 is furthermore provided with a safety system 64 coupledby the communications bus 88 with the processing unit. The safety system64 has a set of sensors (not shown) whose signals transmitted to theprocessing unit 50 enable this unit to control the emergency stoppingsystem of the mobile base 16 and the moving parts of the machine 10 ifnecessary. The sensors in the safety system 64 may be anti-collision andtilt sensors (not shown), and may be formed by an inclinometer, animpact sensor and/or a laser sensor.

The processing unit 50 is furthermore coupled with a device 65 forcontrolling the moving parts of the machine 10. The coupling of theprocessing unit 50 with the control device 65 can be obtained throughthe communications bus 88 or through a radio electrical link. Thiscontrol device 65 may be a joystick or a computer. In one variant, thiscontrol device 65 may be incorporated in the interface 24.

The machine 10 is furthermore provided with a sensor 66 for detectingthe rotation speed of the moving parts. The sensor 66 is coupled with aprocessing unit 50 through the communications bus 88. The signalstransmitted by this sensor 66 to the processing unit 50 enable thisprocessing unit to control the emergency stopping system of the mobilebase 16 and the moving parts of the machine 10 if necessary.

In one embodiment, the activation of the emergency stopping system maybe accompanied by a sound and/or optical alarm system.

The communications bus 88 may be an ‘RS 232’ type series link or an ADC(analogue digital converter) link.

In other words, the automatic driving of the machine 10 is implementedby means of a hardware sequence consisting of positioning sensors suchas traction encoders 61 at each traction motor 34 and 35 respectivelyand direction encoders 60 at each direction motor 42 and 43respectively, the rotational laser scanning sensor 56, the computer 50,the traction variator 62 and direction variator 63 for each turretfeature, the safety sensors and finally the actuators which are thetraction motors 34 and 35 and direction motors 42 and 43.

The non-limiting embodiment of the disclosure described hereinabove thusimplements two distinct navigation systems. One of the navigationsystems is obtained from the traction and direction encoders. The othernavigation system is obtained from the rotary laser scanning sensor.This redundancy of navigation systems makes it possible not only tospecify the absolute position of the X-ray machine but also to improvethe safety system of the machine 10. Indeed, when the difference betweenthe position given by the rotary laser sensor and the position given bythe encoders is greater than a predefined safety threshold, theprocessing unit activates the emergency stopping system of the movingparts of the machine 10 and of the mobile base 16.

The processing unit 50 is a computer device, for example a microcomputerprogrammed to determine the current of the motor according toprogrammable criteria and to fulfill additional functions pertaining tothe management and security of the machine 10.

In the description, when actions are attributed to apparatuses orprograms, it means that these actions are executed by a microprocessorof this apparatus or of the apparatus comprising the program, saidmicroprocessor being then controlled by instruction codes recorded in amemory of the apparatus. These instruction codes are used to implementthe means of the apparatus and therefore to fulfill the actionundertaken.

As illustrated in FIGS. 4-5, the processing unit 50 comprises electroniccircuits 70 connected to the antenna 52. The role of the circuits is toprovide the radio interface between the processing unit and the externalinterfaces.

The processing unit furthermore comprises a microprocessor 71, a programmemory 72 and a data memory 73 connected to a bidirectional bus 74. Theprogram memory 72 is divided into several zones, each zone correspondingto a function or to a mode of operation of the program of the X-raymachine 10 and of the mobile base 16. Similarly, when an action isattributed to a program, this action corresponds to the implementationby a microprocessor, connected to a memory in which the program isrecorded, of all or part of the instruction codes forming said program.

Only the zones of the memory 72 that most directly concern theembodiments described herein are shown.

A zone 75 comprises instruction codes to receive a movement signalcorresponding to the entry of an instructed value of positioning ordestination of the X-ray machine 10. The instructed value of positioningmay be a parking position or a working position coupled with anorientation of the moving parts of the machine 10.

A zone 76 comprises instruction codes to command the gyrolaser uponreception of the shift signal.

A zone 77 comprises instruction codes to extract the coordinates of theposition to be attained by the X-ray machine 10 from the data memory 34,on the basis of the signal received, in the fixed reference system.

A zone 78 comprises instruction codes to interpret the information givenby the gyrolaser in order to determine the initial absolute position ofthe machine 10 in the fixed reference system.

When the initial position determined does not correspond to any parkingor working position pre-recorded in the data memory, the instructioncodes of the zone 78 compute a path to be taken by the mobile base 16 inorder to reach one of positions, namely the parking or the workingposition, on the basis of data given by the encoders and the gyrolaser.In one embodiment, the processing unit computes the shortest path neededto reach the working or parking position closest to the initialposition. A zone 79 comprises instruction codes to extract, from thedata memory 34, a path 67 that the machine 10 must take to link theinitial position with the position to be reached by the X-ray machine10.

A zone 80 comprises instruction codes to determine the relative positionof the machine 10 as a function of the data given by the sensorsinstalled on the mobile base 16.

A zone 81 comprises instruction codes to give each traction motor 34 and35 and each direction motor 42 and 43 a current through the powervariators as a function of the relative position, the initial positionof the machine 10 and the path 67 to be followed.

A zone 82 comprises instruction codes to compute the absolute andrelative positions of the machine 10 at predefined computation periodsall along the path 67 to be followed. A computation period may be of theorder of some milliseconds.

A zone 83 comprises instruction codes to extract a predetermined mappingof the room 9 from the data memory 73.

A zone 84 comprises instruction codes to determine, at each computationperiod, the position of the machine 10 in the mapping as a function ofthe data given by the instruction codes of the zone 83. The instructioncodes of the zone 84 are superimposed on the path to be followed in themapping and determine whether the position of the machine 10 issubstantially in the path. In the event of deflection, the instructioncodes send a compensation command to the variators to command theshifting of the mobile base 16 in the path 67 to be followed.

This embodiment thus makes it possible to move the machine 10 along theextracted path 67 which has been pre-computed. The guiding functionimplemented by the instruction codes of the zone 84 maintain theabsolute position on the path in evaluating the differences in positionbetween the measurement coming from the locating operation and the pathfollowed. The positional direction commands that result from this areapplied to the variators which themselves set up an automatic feedbackcontrol of the motors in position and in speed.

In addition to the guidance, a navigation function can be implemented bythe instruction codes of the zone 84 in order to carry out a schedulingof the traction speeds along the path and transmit control commandsaccordingly to the variators. The variators thus set up an automaticfeedback control between the traction and direction motors.

One part of the safety function is implemented at this level by acoupling between direction and traction. In this case, when thedeviation of the absolute position measured at the path 67 is greaterthan or equal to a predefined threshold of deviation, the speed of themobile base 16 is reduced until it comes to a total halt.

When the machine 10 reaches the position to be reached, a zone 85comprises instruction codes to deactivate the gyrolaser. Theseinstruction codes also send out control commands to the directionvariators so that the wheels are aligned in a predefined idle position.

A zone 86 comprises instruction codes to extract a working orientationsignal of the moving parts, corresponding to the reached workingposition of the X-ray machine, from the positioning instructed value.The instruction codes of the zone 86 are also capable of allowingreception of a work orientation signal for the moving parts of the X-raymachine corresponding to the actuation of the orientation commands ofthe control device 65.

A zone 87 comprises instruction codes to control a system for drivingthe moving parts as a function of the orientation signal. This drivingsystem makes it possible to shift the arms 13, the rotating arm 18, thesupport element 17 and the mobile base 16. The shifting of these parts,which is done as a function of the orientation signal, is done in such away that the organ to be examined remains positioned throughout thediagnosis in the X-ray beam. In one embodiment, the driving system canbe activated during the phases in which the mobile base 16 is beingshifted.

The data memory 73 has a data base 90 in which predetermined parking andworking positions of the machine 10 are recorded. These predeterminedpositions are displayed on the screen by the interface controls. Aparking position is a place where the X-ray machine 10 is placed when itis in parking mode. The parking position removes the X-ray machine fromthe limited space needed for an operation in the room 9. A workingposition is a place in which the X-ray machine 10 is placed during theacquisition of radiography exposures.

The data base 90 is, for example, structured in the form of a table. Forexample, each row of the table corresponds to the coordinates of aposition of an X-ray machine in the fixed reference system, each columnof the table corresponding to a piece of information on this position.Thus, the database 90 comprises: a row 90 a corresponding to thecoordinates of a position in the fixed reference system, a column 90 bcomprising a first field in which a signal of a working position isrecorded, a second field in which an orientation signal correspondingpredetermined working orientations of the moving parts of the X-raymachine 10 are recorded and a third field in which a path to be followedis recorded, and a column 90 c comprising a first field in which aparking signal is recorded, and a second field in which a path to befollowed is recorded.

A working orientation is a configuration of the X-ray machine in whichthe arm 13, the rotating arm 14, the support element 17 and the mobilebase 16 are shifted to a radiography position according to theorientation signal. This shift does not affect the position of the organto be examined relative to the X-ray beam.

The data memory 73 also has a data base 91 in which a mapping of theroom 9 is recorded.

The data/memory bases have been represented only by way of anillustration of the layout of components and data recordings. Inpractice, these memories are unified and distributed according toconstraints of size of the data base and/or the speed of the processingoperations desired.

The described embodiments are not limited to the descriptionhereinabove. Indeed, in one embodiment, the man-machine interface 24 maybe supplemented or replaced by a joystick-type control lever with threedegrees of freedom, along two orthogonal directions and one rotation atan angle θ. The joystick can be mounted on the mobile base 16 or set offat a distance.

The communication between the joystick and the processing unit 50 can bedone through a radioelectrical link or a wire link such as a serieslink. For example, the joystick can send control signals to theprocessing unit 50.

The joystick may comprise a base unit and a unit forming a movablehandle that can be tilted in every direction and can be manipulatedalong several degrees of freedom. Under the effect of the movement ofthe unit forming a handle relative to the base unit, the processing unitsends the traction variator 62 and direction variator 63 respectivelyinstructed values of speed and direction which they convert into currentand voltage for each motor. A movement of the handle-forming unitrelative to the base unit in one direction activates a command formoving the mobile base 16 in one direction or another depending on thedirection of shift programmed in the processing unit 50.

The joystick is thus capable of controlling the movements of the mobilebase 16 in the room 9 according to signals received by the processingunit 50.

As shown in FIG. 12, the positioning system 105 comprises a gyrolaser56, a reading system 59 and a memory 110. The positioning system 105 isconfigured to compute position data corresponding to a position of themedical imaging machine, such as an X-ray machine, 10 in a predefinedfixed referential system on the basis of reflections from reflectors 58positioned about a defined space, room 9. The positions of thereflectors 58 are stored in the memory 110.

The processing unit 50 in turn is in communication with the at least twomotorized drive wheels 36, 37 and the positioning system 105. Theprocessing unit 50 is able to receive position data provided by thepositioning system 105, as well as generate an output of a respectivecommand (e.g. a drive command comprising speed, position and/orrotational direction information) for each the at least two motorizedwheels 36, 37 to position and orient the mobile base 16. The output mayalso set the speed of one or both of the wheels. The processing unit 50is also able to receive inputs from a user. Such inputs includeinstruction values corresponding to at least one of destination,trajectory, and orientation of the mobile base 16.

The data provided by the gyrolaser to the processing unit 50 can be usedto find out the geographical position of the machine 10 in the room 9 inreal time in order to prevent possible collisions for example with theexamination table 14.

In one alternative embodiment, the interface 24 may be supplemented orreplaced by a remote control wireless type control lever capable ofsteering the movement of the mobile base 16 in two orthogonal directionsand a rotation by an angle θ.

This written description uses examples to disclose several embodimentsof the invention, including the best mode, and also to enable one ofordinary skill in the art to practice the embodiments of invention,including making and using any devices or systems and performing anyincorporated methods. The patentable scope of the invention is definedby the claims, and may include other examples that occur to one ofordinary skill in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral languages of the claims.

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralof said elements or steps, unless such exclusion is explicitly stated.Furthermore, references to “one embodiment” of the present disclosure orinvention are not intended to be interpreted as excluding the existenceof additional embodiments that also incorporate the recited features.Moreover, unless explicitly stated to the contrary, embodiments“comprising,” “including,” or “having” an element or a plurality ofelements having a particular property may include additional suchelements not having that property.

Since certain changes may be made in the above-described embodiments,without departing from the spirit and scope of the invention hereininvolved, it is intended that all of the subject matter of the abovedescription shown in the accompanying drawings shall be interpretedmerely as examples illustrating the inventive concept herein and shallnot be construed as limiting the invention.

What is claimed is:
 1. A mobile base to support a medical imagingmachine comprising: at least two motorized drive wheels spaced away fromeach other, each of the at least two motorized drive wheels configuredto rotate independently of one another in either rotational directionrelative to a respective axis of rotation; a positioning systemcomprising a gyrolaser, a reading system and a memory, the positioningsystem configured to compute position data corresponding to a positionof the medical imaging machine in a predefined fixed referential systemon the basis of reflections from reflectors positioned about a definedspace, the positions of the reflectors stored in the memory; and aprocessing unit in communication with the at least two motorized drivewheels and the positioning system, and configured to receive theposition data and to generate as an output a respective command for eachof the at least two wheel motorized drive wheels to move and orient themobile base to one or more desired positions in the defined space. 2.The mobile base of claim 1, further comprising a traction encodermounted on the at least two motorized drive wheels and a directionencoder, wherein the traction encoder and the direction encoder areconfigured to provide data relative to a position of the X-ray machine.3. The mobile base of claim 2, further comprising a support structurecomprising: a supporting arm comprising an upper end to which the X-raymachine is designed to be fixed; and a set of structural parts restingon the floor comprising at least one wheel and being assembled with thesupporting arm, wherein the supporting arm and the set of structuralparts are configured to give the mobile base mechanical characteristicsof rigidity relative to the supporting arm.
 4. The mobile base of claim3, wherein the set of structural parts comprises: a baseplate fixed tothe supporting arm, the baseplate comprising a horizontal plate on whichthe at least two motorized drive wheels are installed; a crossbarfixedly joined to the baseplate; and an element with two arms having anangle and being fixedly joined to the crossbar, the arms being situatedon a front part of the X-ray machine.
 5. The mobile base of claim 4,wherein the element with two arms is positioned at a determined distanceso that the front ends of the arms do not collide with an X-ray tube,and the distance between the tube and an isocenter of the X-ray machineis maximized.
 6. The mobile base of claim 4, further comprising at leastone freewheel mounted on one end of each arm on a face before theground, wherein the at least one freewheel is mounted so that arotational axis of the at least one freewheel is off-center relative toa supporting base of the at least one freewheel on the ground.
 7. Themobile base of claim 6, further comprising a braking apparatus mountedon the at least one freewheel, wherein the braking apparatus isconfigured to block the rotation of the at least one freewheel and keepthe at least one freewheel stopped.
 8. The mobile base of claim 1,further comprising a braking apparatus configured to stop the mobilebase when moving and/or prevent the base from moving from a parkedposition.
 9. The mobile base of claim 1, further comprising a userinterface in communication with the processing unit for entering atleast one of instructed values of destination and instructed values oftrajectory.
 10. The mobile base of claim 9, wherein the user interfaceis embedded in the mobile base or placed at a distance from the mobilebase.
 11. The mobile base of claim 1, wherein the mobile base iselectrically powered.
 12. The mobile base of claim 1, further comprisinga safety system comprising anti-collision and tilt sensors.
 13. Themobile base of claim 1, wherein the at least two drive wheels areconfigured to rotate at the same speed or at variable speeds relative toone another.
 14. The mobile base of claim 1, wherein the processing unitis also configured to receive inputs from a user.
 15. The mobile base ofclaim 14, wherein the processing unit is further configured to receiveinstruction values corresponding to at least one of destination,trajectory, speed, position and orientation of the mobile base.
 16. AnX-ray machine comprising: an X-ray tube configured to emit an X-ray beamalong a direction of emission; and an X-ray detector aligned in thedirection of emission of the X-ray beam and positioned to face the X-raytube, wherein the X-ray machine is mounted on a mobile base comprising:at least two motorized drive wheels spaced away from each other, each ofthe at least two motorized drive wheels configured to rotateindependently of one another in either rotational direction relative toa respective axis of rotation; a positioning system comprising agyrolaser, a reading system and a memory, the positioning systemconfigured to compute position data corresponding to a position of themedical imaging machine in a predefined fixed referential system on thebasis of reflections from reflectors positioned about a defined space,the positions of the reflectors stored in the memory; and a processingunit in communication with the at least two motorized drive wheels andthe positioning system, and configured to receive the position data andto generate as an output a respective command for each of the at leasttwo wheel motorized drive wheels to move and orient the mobile base toone or more desired positions in the defined space.
 17. The X-raymachine of claim 16, wherein the at least two drive wheels areconfigured to rotate at the same speed or at variable speeds relative toone another.
 18. A mobile platform comprising: at least two motorizeddrive wheels spaced away from each other, each of the at least twomotorized drive wheels configured to rotate independently of one anotherin either rotational direction relative to a respective axis ofrotation; a positioning system comprising a gyrolaser, a reading systemand a memory, the positioning system configured to compute position datacorresponding to a position of the mobile platform in a predefined fixedreferential system on the basis of reflections from reflectorspositioned about a defined space, the positions of the reflectors storedin the memory; and a processing unit in communication with the at leasttwo motorized drive wheels and the positioning system, and configured toreceive the position data and to generate as an output a respectivecommand for each of the at least two wheel motorized drive wheels tomove and orient the mobile platform to one or more desired positions inthe defined space.
 19. The mobile platform of claim 18, wherein the atleast two drive wheels are configured to rotate at the same speed or atvariable speeds relative to one another.